Experimental study on the combined shear and bending behaviour of corbel joints in precast concrete segmental inverted-T caps

Abstract

Precast construction of caps is adopted to reduce on-site construction time and facilitate installation. A corbel joint (CJ) is proposed as an innovative joint form to improve the mechanical behaviour and construction performance of precast concrete segmental inverted-T caps. To obtain a further understanding of the failure modes and resistance mechanisms of CJs subjected to combined shear and bending, eight cap specimens with different shear-span ratios (1.61, 2.37, and 3.89) and joint types (CJ, monolithic concrete, and straight joints with a single tooth or multiple teeth) were match cast and tested. The experimental results showed that the CJs achieved superior mechanical and deformation performance and higher bearing capacity compared to conventional straight joints. Owing to corbels intercepting cracks, the CJs were not fully opened similar to straight joints at the limit state. Furthermore, the reinforcement in the corbels reached the yield strength, which suggested that the CJs could transfer the shear force between two adjacent segments effectively and reliably. When the shear-span ratios changed from 1.61 to 3.89, the ultimate shear force in the joint plane reduced by 57.9%, while the ultimate bending moment increased by 5.2%. Therefore, the ultimate shear and bending moment of the CJs were correlated.